JTAG ICE mkII problems with Win 7 x64

Been having some wierd issues with the JTAG ICE mkII with crossworks.

I've tried many times attempting to connect to target, and in each instance it has reported: "No JTAGICE MkII's detected", AVRStudio detects the JTAGICE and will read the target voltage but has problems programming.

I've tried re-installing the drivers, removing drivers then installing again, but with no prevail. I've also tried it with several USB ports, any ideas?